Spanish patent P201000275 describes a source of renewable energy for the production of mechanical or electrical energy, comprising a duct submerged in a fluid, generally water, contained within another tube or vessel, whose outlet section is approximately at the same level as the free surface of the water, and its inlet at a lower level. The system likewise features an element which introduces a fluid of lower density, usually air, into the interior of this duct, by means of bubbles of uniform size, and preferably of relatively small size, approximately in the same direction as the duct and occupying the entirety of its profile, which brings about the upward mobility of said fluid (air-water mixture) towards the surface. The upward mobility is due to the hydrostatic upthrust exerted by the water outside the duct (greater density) from the lower section of the duct on the fluid (air-water mixture) located within the duct, this featuring a lower density. Thus, as in Archimedes' upthrust, the air bubbles borne by the water situated within the duct transmit part of their upthrust to the water. The energy of this induced flow is what is harnessed, as is the static and dynamic pressure of the fluid with the lower density, generally air, which is fed into the duct under static and dynamic pressure.